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+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * AEAD: Authenticated Encryption with Associated Data
+ *
+ * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#ifndef _CRYPTO_AEAD_H
+#define _CRYPTO_AEAD_H
+
+#include <linux/crypto.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+/**
+ * DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API
+ *
+ * The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD
+ * (listed as type "aead" in /proc/crypto)
+ *
+ * The most prominent examples for this type of encryption is GCM and CCM.
+ * However, the kernel supports other types of AEAD ciphers which are defined
+ * with the following cipher string:
+ *
+ * authenc(keyed message digest, block cipher)
+ *
+ * For example: authenc(hmac(sha256), cbc(aes))
+ *
+ * The example code provided for the symmetric key cipher operation
+ * applies here as well. Naturally all *skcipher* symbols must be exchanged
+ * the *aead* pendants discussed in the following. In addition, for the AEAD
+ * operation, the aead_request_set_ad function must be used to set the
+ * pointer to the associated data memory location before performing the
+ * encryption or decryption operation. In case of an encryption, the associated
+ * data memory is filled during the encryption operation. For decryption, the
+ * associated data memory must contain data that is used to verify the integrity
+ * of the decrypted data. Another deviation from the asynchronous block cipher
+ * operation is that the caller should explicitly check for -EBADMSG of the
+ * crypto_aead_decrypt. That error indicates an authentication error, i.e.
+ * a breach in the integrity of the message. In essence, that -EBADMSG error
+ * code is the key bonus an AEAD cipher has over "standard" block chaining
+ * modes.
+ *
+ * Memory Structure:
+ *
+ * The source scatterlist must contain the concatenation of
+ * associated data || plaintext or ciphertext.
+ *
+ * The destination scatterlist has the same layout, except that the plaintext
+ * (resp. ciphertext) will grow (resp. shrink) by the authentication tag size
+ * during encryption (resp. decryption).
+ *
+ * In-place encryption/decryption is enabled by using the same scatterlist
+ * pointer for both the source and destination.
+ *
+ * Even in the out-of-place case, space must be reserved in the destination for
+ * the associated data, even though it won't be written to. This makes the
+ * in-place and out-of-place cases more consistent. It is permissible for the
+ * "destination" associated data to alias the "source" associated data.
+ *
+ * As with the other scatterlist crypto APIs, zero-length scatterlist elements
+ * are not allowed in the used part of the scatterlist. Thus, if there is no
+ * associated data, the first element must point to the plaintext/ciphertext.
+ *
+ * To meet the needs of IPsec, a special quirk applies to rfc4106, rfc4309,
+ * rfc4543, and rfc7539esp ciphers. For these ciphers, the final 'ivsize' bytes
+ * of the associated data buffer must contain a second copy of the IV. This is
+ * in addition to the copy passed to aead_request_set_crypt(). These two IV
+ * copies must not differ; different implementations of the same algorithm may
+ * behave differently in that case. Note that the algorithm might not actually
+ * treat the IV as associated data; nevertheless the length passed to
+ * aead_request_set_ad() must include it.
+ */
+
+struct crypto_aead;
+
+/**
+ * struct aead_request - AEAD request
+ * @base: Common attributes for async crypto requests
+ * @assoclen: Length in bytes of associated data for authentication
+ * @cryptlen: Length of data to be encrypted or decrypted
+ * @iv: Initialisation vector
+ * @src: Source data
+ * @dst: Destination data
+ * @__ctx: Start of private context data
+ */
+struct aead_request {
+ struct crypto_async_request base;
+
+ unsigned int assoclen;
+ unsigned int cryptlen;
+
+ u8 *iv;
+
+ struct scatterlist *src;
+ struct scatterlist *dst;
+
+ void *__ctx[] CRYPTO_MINALIGN_ATTR;
+};
+
+/**
+ * struct aead_alg - AEAD cipher definition
+ * @maxauthsize: Set the maximum authentication tag size supported by the
+ * transformation. A transformation may support smaller tag sizes.
+ * As the authentication tag is a message digest to ensure the
+ * integrity of the encrypted data, a consumer typically wants the
+ * largest authentication tag possible as defined by this
+ * variable.
+ * @setauthsize: Set authentication size for the AEAD transformation. This
+ * function is used to specify the consumer requested size of the
+ * authentication tag to be either generated by the transformation
+ * during encryption or the size of the authentication tag to be
+ * supplied during the decryption operation. This function is also
+ * responsible for checking the authentication tag size for
+ * validity.
+ * @setkey: see struct skcipher_alg
+ * @encrypt: see struct skcipher_alg
+ * @decrypt: see struct skcipher_alg
+ * @ivsize: see struct skcipher_alg
+ * @chunksize: see struct skcipher_alg
+ * @init: Initialize the cryptographic transformation object. This function
+ * is used to initialize the cryptographic transformation object.
+ * This function is called only once at the instantiation time, right
+ * after the transformation context was allocated. In case the
+ * cryptographic hardware has some special requirements which need to
+ * be handled by software, this function shall check for the precise
+ * requirement of the transformation and put any software fallbacks
+ * in place.
+ * @exit: Deinitialize the cryptographic transformation object. This is a
+ * counterpart to @init, used to remove various changes set in
+ * @init.
+ * @base: Definition of a generic crypto cipher algorithm.
+ *
+ * All fields except @ivsize is mandatory and must be filled.
+ */
+struct aead_alg {
+ int (*setkey)(struct crypto_aead *tfm, const u8 *key,
+ unsigned int keylen);
+ int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);
+ int (*encrypt)(struct aead_request *req);
+ int (*decrypt)(struct aead_request *req);
+ int (*init)(struct crypto_aead *tfm);
+ void (*exit)(struct crypto_aead *tfm);
+
+ unsigned int ivsize;
+ unsigned int maxauthsize;
+ unsigned int chunksize;
+
+ struct crypto_alg base;
+};
+
+struct crypto_aead {
+ unsigned int authsize;
+ unsigned int reqsize;
+
+ struct crypto_tfm base;
+};
+
+static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
+{
+ return container_of(tfm, struct crypto_aead, base);
+}
+
+/**
+ * crypto_alloc_aead() - allocate AEAD cipher handle
+ * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
+ * AEAD cipher
+ * @type: specifies the type of the cipher
+ * @mask: specifies the mask for the cipher
+ *
+ * Allocate a cipher handle for an AEAD. The returned struct
+ * crypto_aead is the cipher handle that is required for any subsequent
+ * API invocation for that AEAD.
+ *
+ * Return: allocated cipher handle in case of success; IS_ERR() is true in case
+ * of an error, PTR_ERR() returns the error code.
+ */
+struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
+
+static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
+{
+ return &tfm->base;
+}
+
+/**
+ * crypto_free_aead() - zeroize and free aead handle
+ * @tfm: cipher handle to be freed
+ *
+ * If @tfm is a NULL or error pointer, this function does nothing.
+ */
+static inline void crypto_free_aead(struct crypto_aead *tfm)
+{
+ crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
+}
+
+static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
+{
+ return container_of(crypto_aead_tfm(tfm)->__crt_alg,
+ struct aead_alg, base);
+}
+
+static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
+{
+ return alg->ivsize;
+}
+
+/**
+ * crypto_aead_ivsize() - obtain IV size
+ * @tfm: cipher handle
+ *
+ * The size of the IV for the aead referenced by the cipher handle is
+ * returned. This IV size may be zero if the cipher does not need an IV.
+ *
+ * Return: IV size in bytes
+ */
+static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
+{
+ return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
+}
+
+/**
+ * crypto_aead_authsize() - obtain maximum authentication data size
+ * @tfm: cipher handle
+ *
+ * The maximum size of the authentication data for the AEAD cipher referenced
+ * by the AEAD cipher handle is returned. The authentication data size may be
+ * zero if the cipher implements a hard-coded maximum.
+ *
+ * The authentication data may also be known as "tag value".
+ *
+ * Return: authentication data size / tag size in bytes
+ */
+static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
+{
+ return tfm->authsize;
+}
+
+static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)
+{
+ return alg->maxauthsize;
+}
+
+static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)
+{
+ return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead));
+}
+
+/**
+ * crypto_aead_blocksize() - obtain block size of cipher
+ * @tfm: cipher handle
+ *
+ * The block size for the AEAD referenced with the cipher handle is returned.
+ * The caller may use that information to allocate appropriate memory for the
+ * data returned by the encryption or decryption operation
+ *
+ * Return: block size of cipher
+ */
+static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
+{
+ return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
+}
+
+static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
+{
+ return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
+}
+
+static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
+{
+ return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
+}
+
+static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
+{
+ crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
+}
+
+static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
+{
+ crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
+}
+
+/**
+ * crypto_aead_setkey() - set key for cipher
+ * @tfm: cipher handle
+ * @key: buffer holding the key
+ * @keylen: length of the key in bytes
+ *
+ * The caller provided key is set for the AEAD referenced by the cipher
+ * handle.
+ *
+ * Note, the key length determines the cipher type. Many block ciphers implement
+ * different cipher modes depending on the key size, such as AES-128 vs AES-192
+ * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
+ * is performed.
+ *
+ * Return: 0 if the setting of the key was successful; < 0 if an error occurred
+ */
+int crypto_aead_setkey(struct crypto_aead *tfm,
+ const u8 *key, unsigned int keylen);
+
+/**
+ * crypto_aead_setauthsize() - set authentication data size
+ * @tfm: cipher handle
+ * @authsize: size of the authentication data / tag in bytes
+ *
+ * Set the authentication data size / tag size. AEAD requires an authentication
+ * tag (or MAC) in addition to the associated data.
+ *
+ * Return: 0 if the setting of the key was successful; < 0 if an error occurred
+ */
+int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
+
+static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
+{
+ return __crypto_aead_cast(req->base.tfm);
+}
+
+/**
+ * crypto_aead_encrypt() - encrypt plaintext
+ * @req: reference to the aead_request handle that holds all information
+ * needed to perform the cipher operation
+ *
+ * Encrypt plaintext data using the aead_request handle. That data structure
+ * and how it is filled with data is discussed with the aead_request_*
+ * functions.
+ *
+ * IMPORTANT NOTE The encryption operation creates the authentication data /
+ * tag. That data is concatenated with the created ciphertext.
+ * The ciphertext memory size is therefore the given number of
+ * block cipher blocks + the size defined by the
+ * crypto_aead_setauthsize invocation. The caller must ensure
+ * that sufficient memory is available for the ciphertext and
+ * the authentication tag.
+ *
+ * Return: 0 if the cipher operation was successful; < 0 if an error occurred
+ */
+int crypto_aead_encrypt(struct aead_request *req);
+
+/**
+ * crypto_aead_decrypt() - decrypt ciphertext
+ * @req: reference to the aead_request handle that holds all information
+ * needed to perform the cipher operation
+ *
+ * Decrypt ciphertext data using the aead_request handle. That data structure
+ * and how it is filled with data is discussed with the aead_request_*
+ * functions.
+ *
+ * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
+ * authentication data / tag. That authentication data / tag
+ * must have the size defined by the crypto_aead_setauthsize
+ * invocation.
+ *
+ *
+ * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
+ * cipher operation performs the authentication of the data during the
+ * decryption operation. Therefore, the function returns this error if
+ * the authentication of the ciphertext was unsuccessful (i.e. the
+ * integrity of the ciphertext or the associated data was violated);
+ * < 0 if an error occurred.
+ */
+int crypto_aead_decrypt(struct aead_request *req);
+
+/**
+ * DOC: Asynchronous AEAD Request Handle
+ *
+ * The aead_request data structure contains all pointers to data required for
+ * the AEAD cipher operation. This includes the cipher handle (which can be
+ * used by multiple aead_request instances), pointer to plaintext and
+ * ciphertext, asynchronous callback function, etc. It acts as a handle to the
+ * aead_request_* API calls in a similar way as AEAD handle to the
+ * crypto_aead_* API calls.
+ */
+
+/**
+ * crypto_aead_reqsize() - obtain size of the request data structure
+ * @tfm: cipher handle
+ *
+ * Return: number of bytes
+ */
+static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
+{
+ return tfm->reqsize;
+}
+
+/**
+ * aead_request_set_tfm() - update cipher handle reference in request
+ * @req: request handle to be modified
+ * @tfm: cipher handle that shall be added to the request handle
+ *
+ * Allow the caller to replace the existing aead handle in the request
+ * data structure with a different one.
+ */
+static inline void aead_request_set_tfm(struct aead_request *req,
+ struct crypto_aead *tfm)
+{
+ req->base.tfm = crypto_aead_tfm(tfm);
+}
+
+/**
+ * aead_request_alloc() - allocate request data structure
+ * @tfm: cipher handle to be registered with the request
+ * @gfp: memory allocation flag that is handed to kmalloc by the API call.
+ *
+ * Allocate the request data structure that must be used with the AEAD
+ * encrypt and decrypt API calls. During the allocation, the provided aead
+ * handle is registered in the request data structure.
+ *
+ * Return: allocated request handle in case of success, or NULL if out of memory
+ */
+static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
+ gfp_t gfp)
+{
+ struct aead_request *req;
+
+ req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
+
+ if (likely(req))
+ aead_request_set_tfm(req, tfm);
+
+ return req;
+}
+
+/**
+ * aead_request_free() - zeroize and free request data structure
+ * @req: request data structure cipher handle to be freed
+ */
+static inline void aead_request_free(struct aead_request *req)
+{
+ kfree_sensitive(req);
+}
+
+/**
+ * aead_request_set_callback() - set asynchronous callback function
+ * @req: request handle
+ * @flags: specify zero or an ORing of the flags
+ * CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
+ * increase the wait queue beyond the initial maximum size;
+ * CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
+ * @compl: callback function pointer to be registered with the request handle
+ * @data: The data pointer refers to memory that is not used by the kernel
+ * crypto API, but provided to the callback function for it to use. Here,
+ * the caller can provide a reference to memory the callback function can
+ * operate on. As the callback function is invoked asynchronously to the
+ * related functionality, it may need to access data structures of the
+ * related functionality which can be referenced using this pointer. The
+ * callback function can access the memory via the "data" field in the
+ * crypto_async_request data structure provided to the callback function.
+ *
+ * Setting the callback function that is triggered once the cipher operation
+ * completes
+ *
+ * The callback function is registered with the aead_request handle and
+ * must comply with the following template::
+ *
+ * void callback_function(struct crypto_async_request *req, int error)
+ */
+static inline void aead_request_set_callback(struct aead_request *req,
+ u32 flags,
+ crypto_completion_t compl,
+ void *data)
+{
+ req->base.complete = compl;
+ req->base.data = data;
+ req->base.flags = flags;
+}
+
+/**
+ * aead_request_set_crypt - set data buffers
+ * @req: request handle
+ * @src: source scatter / gather list
+ * @dst: destination scatter / gather list
+ * @cryptlen: number of bytes to process from @src
+ * @iv: IV for the cipher operation which must comply with the IV size defined
+ * by crypto_aead_ivsize()
+ *
+ * Setting the source data and destination data scatter / gather lists which
+ * hold the associated data concatenated with the plaintext or ciphertext. See
+ * below for the authentication tag.
+ *
+ * For encryption, the source is treated as the plaintext and the
+ * destination is the ciphertext. For a decryption operation, the use is
+ * reversed - the source is the ciphertext and the destination is the plaintext.
+ *
+ * The memory structure for cipher operation has the following structure:
+ *
+ * - AEAD encryption input: assoc data || plaintext
+ * - AEAD encryption output: assoc data || cipherntext || auth tag
+ * - AEAD decryption input: assoc data || ciphertext || auth tag
+ * - AEAD decryption output: assoc data || plaintext
+ *
+ * Albeit the kernel requires the presence of the AAD buffer, however,
+ * the kernel does not fill the AAD buffer in the output case. If the
+ * caller wants to have that data buffer filled, the caller must either
+ * use an in-place cipher operation (i.e. same memory location for
+ * input/output memory location).
+ */
+static inline void aead_request_set_crypt(struct aead_request *req,
+ struct scatterlist *src,
+ struct scatterlist *dst,
+ unsigned int cryptlen, u8 *iv)
+{
+ req->src = src;
+ req->dst = dst;
+ req->cryptlen = cryptlen;
+ req->iv = iv;
+}
+
+/**
+ * aead_request_set_ad - set associated data information
+ * @req: request handle
+ * @assoclen: number of bytes in associated data
+ *
+ * Setting the AD information. This function sets the length of
+ * the associated data.
+ */
+static inline void aead_request_set_ad(struct aead_request *req,
+ unsigned int assoclen)
+{
+ req->assoclen = assoclen;
+}
+
+#endif /* _CRYPTO_AEAD_H */